Transcript Slide 1
Re-Examination of Visions for
Tokamak Power Plants –
The ARIES-ACT Study
Farrokh Najmabadi
Professor of Electrical & Computer Engineering
Director, Center for Energy Research
UC San Diego
and the ARIES Team
TOFE 2012
August 30, 2012
ARIES Program Participants
Systems code: UC San Diego, PPPL
Plasma Physics: PPPL , GA, LLNL
Fusion Core Design & Analysis: UC San Diego, FNT Consulting
Nuclear Analysis: UW-Madison
Plasma Facing Components (Design & Analysis): UC San Diego, UWMadison
Plasma Facing Components (experiments): Georgia Tech
Design Integration: UC San Diego, Boeing
Safety: INEL
Contact to Material Community: ORNL
Goals of ARIES ACT Study
Over a decade since last tokamak study : ARIES-1 (1990)
through ARIES-AT(2000).
Substantial progress in understanding in many areas.
New issues have emerged: e.g., edge plasma physics, PMI,
PFCs, and off-normal events.
o What would be the maximum fluxes that can be handled by invessel components in a power plant?
o What level of off-normal events are acceptable in a commercial
power plant?
Evolving needs in the ITER and FNSF/Demo era:
Risk/benefit analysis among extrapolation and attractiveness.
Detailed component designs is necessary to understand R&D
requirements.
Frame the “parameter space for
attractive power plants” by considering
the “four corners” of parameter space
Reversed-shear
(βN=0.04-0.06)
DCLL blanket
Reversed-shear
(βN=0.04-0.06)
SiC blanket
1st Stability
(no-wall limit)
DCLL blanket
1st Stability
(no-wall limit)
SiC blanket
ARIES-RS/AT
SSTR-2
EU Model-D
Physics
Extrapolation
Higher power density
Higher density
Lower current-drive power
Lower power density
Lower density
Higher CD power
Lower thermal efficiency
Higher Fusion/plasma power
Higher P/R
Metallic first wall/blanket
Engineering
performance
(efficiency)
ARIES-1
SSTR
Higher thermal efficiency
Lower fusion/plasma power
Lower P/R
Composite first wall/blanket
Status of the ARIES ACT Study
Project Goals:
Detailed design of advanced physics, SiC blanket ACT-1
(ARIES-AT update).
Detailed design of ACT-2 (conservative physics, DCLL
blanket).
System-level definitions for ACT-3 & ACT-4.
ACT-1 research will be completed by Dec. 2012.
First design iteration was completed for a 5.5 m Device.
Updated design point at R = 6.25 m (detailed design on-going)
9 papers in this conference.
ACT-2 Research will be completed by June 2013.
ARIES-ACT1 (ARIES-AT update)
Advance tokamak mode
Blanket: SiC structure & LiPb Coolant/breeder
(to achieve a high efficiency)
ARIES Systems Code – a new
approach to finding operating points
Systems codes find a single
operating point through a
minimization of a figure of
merit with certain constraints
Very difficult to see sensitivity
to assumptions.
Our new approach to systems
analysis is based on surveying
the design space and finding a
large number of viable
operating points.
A GUI is developed to
visualize the data. It can
impose additional constraints
to explore sensitivities
Example: Data base of operating points with
fbs ≤ 0.90, 0.85 ≤ fGW ≤ 1.0, H98 ≤ 1.75
Impact of the Divertor Heat load
Divertor design can handle > 10 MW/m2
peak load.
UEDGE simulations (LLNL) showed
detached divertor solution to reach high
radiated powers in the divertor slot and
a low peak heat flux on the divertor
(~5MW/m2 peak).
Leads to ARIES-AT-size device at
R=5.5m.
Control & sustaining a detached divertor?
Using Fundamenski SOL estimates and
90% radiation in SOL+divertor leads to
a 6.25-m device with only 4 mills cost
penalty (current reference point).
Device size is set by the divertor heat flux
The new systems approach
underlines robustness of the design
point to physics achievements
Major radius (m)
6.25
6.25
Aspect ratio
4
4
Toroidal field on axis (T)
6
7
Peak field on the coil (T)
11.8
12.9
5.75%
4.75%
Plasma current (MA)
10.9
10.9
H98
1.65
1.58
Fusion power (MW)
1813
1817
Auxiliary power
154
169
Average n wall load (MW/m2)
2.3
2.3
Peak divertor heat flux (MW/m2)
10.6
11.0
Cost of Electricity (mills/kWh)
67.2
68.9
Normalized beta*
* Includes fast a contribution of ~ 1%
The new systems approach
underlines robustness of the design
point to physics achievements
Major radius (m)
6.25
6.25
Aspect ratio
4
4
Toroidal field on axis (T)
6
7
Peak field on the coil (T)
11.8
12.9
5.75%
4.75%
Plasma current (MA)
10.9
10.9
H98
1.65
1.58
Fusion power (MW)
1813
1817
Auxiliary power
154
169
Average n wall load (MW/m2)
2.3
2.3
Peak divertor heat flux (MW/m2)
10.6
11.0
Cost of Electricity (mills/kWh)
67.2
68.9
Normalized beta*
* Includes fast a contribution of ~ 1%
Detailed Physics analysis has been
performed using the latest tools
New physics modeling
Energy transport assessment: what is
required and model predictions
Pedestal treatment
Time-dependent free boundary
simulations of formation and
operating point
Edge plasma simulation (consistent
divertor/edge, detachment, etc)
Divertor/FW heat loading from
experimental tokamaks for transient
and off-normal*
Disruption simulations*
Fast particle MHD
* Discussed in the paper by C. Kessel, this session
Overview of engineering design:
1. High-hest flux components*
Design of first wall and divertor options
High-performance He-cooled W-alloy
divertor, external transition to steel
Robust FW concept (embedded W pins)
Analysis of first wall and divertor
options
Birth-to-death modeling
Yield, creep, fracture mechanics
Failure modes
Helium heat transfer experiments
ELM and disruption loading responses
Thermal, mechanical, EM &
ferromagnetic
* Discussed in papers by M. Tillack and J. Blanchard,
this session
Overview of engineering design*:
2. Fusion Core
Features similar to ARIES-AT
PbLi self-cooled SiC/SiC breeding blanket
with simple double-pipe construction
Brayton cycle with h~60%
Many new features and improvements
He-cooled ferritic steel structural ring/shield
Detailed flow paths and manifolding for
PbLi to reduce 3D MHD effects**
Elimination of water from the vacuum
vessel, separation of vessel and shield
Identification of new material for the
vacuum vessel***
* Discussed in the paper by M. Tillack, this session
** Discussed in the paper by X. Wang, this session
*** Discussed in the paper by L. El_Guebaly, this session
Detailed safety analysis has highlighted
impact of tritium absorption and transport
Detailed safety modeling of ARIES-AT (Petti et al) and
ARIES-CS (Merrill et al, FS&T, 54, 2008 ) have shown a
paradigm shift in safety issues:
Use of low-activation material and care design has limited
temperature excursions and mobilization of radioactivity
during accidents. Rather off-site dose is dominated by
tritium.
For ARIES-CS worst-case accident, tritium release dose is
8.5 mSv (no-evacuation limit is 10 mSV)
Major implications for material and component R&D:
Need to minimize tritium inventory (control of breeding,
absorption and inventory in different material)
Design implications: material choices, in-vessel
components, vacuum vessel, etc.
In summary …
ARIES-ACT study is re-examining the tokamak power plant
space to understand risk and trade-offs of higher physics and
engineering performance with special emphais on PMI/PFC
and off-normal events.
ARIES-ACT1 (updated ARIES-AT) is near completion.
Detailed physics analysis with modern computational tools are
used. Many new physics issues are included.
The new system approach indicate a robust design window for this
class of power plants.
Many engineering imporvements: He-cooled ferritic steel structural
ring/shield, Detailed flow paths and manifolding to reduce 3D MHD
effects, Identification of new material for the vacuum vessel …
In-elastic analysis of component including Birth-to-death modeling
and fracture mechanics indicate a higher performance PFCs are
possible. Many issues/properties for material development &
optimization are identified.
Thank you!